The invention relates to a hand-operated jigsaw. These types of jigsaws are embodied, for example, as all-purpose saws.
Known from European Patent Document No. EP 0 561 473 B1, which is the point of departure of the present invention, is a generic electric hand-operated jigsaw with a drive arrangement for producing a pendulum action. The drive arrangement includes a reciprocating drive mechanism for a reciprocating body embodied as a reciprocating rod. A tool receptacle for a saw blade is fixed on a free end of the reciprocating body in this case. The reciprocating drive mechanism comprises an eccentric wheel embodied as a bevel gear, on which an eccentric pin is arranged, which engages on the reciprocating body. To counterbalance the vibrations generated during operation of the jigsaw, a counterbalancing mass that is operated in a reciprocating motion is provided, which is put into a reciprocating motion that is phase-offset by 180° to the reciprocating motion of the reciprocating body via the eccentric drive mechanism along a movement axis defined by the reciprocating body.
The disadvantage of this known jigsaw is its high weight, which is caused by providing the counterbalancing mass and the additional components required for it.
The objective of the present invention is developing a jigsaw of the aforementioned type that has a lower weight and is simultaneously able to reduce vibrations well.
Accordingly, the additional mass is arranged in a rotationally fixed manner with the eccentric wheel on the pivot bearing axis, wherein an eccentric axis of the eccentric lies on a first radial of the pivot bearing axis, which is offset from a second radial, which lies between the mass center of gravity of the additional mass and the pivot bearing axis, in the operating direction of rotation of the eccentric wheel at an angle of between 190° and 270°. This permits, for one, a lower total weight to be achieved, because it is possible to dispense with additional components such as, for example, guiding means for an axially guided additional mass. Furthermore, the additional mass itself can have a lower weight as compared to an axially guided additional mass, wherein, through the co-rotating additional mass which is offset at an angle from the eccentric, a maximum compensation for the vibrations in both vector directions of the plane spanning through the housing and the main hand grip is achieved.
The angle between the first radial and the second radial is advantageously between 195° and 225°, thereby further optimizing the compensation for the vibrations.
In an embodiment that is simple in terms of manufacturing, the additional mass is embodied as one piece with the eccentric wheel, whereby a cost reduction can be achieved.
An improvement in the compensation for vibrations can also be achieved if the eccentric wheel, which spans a plane, is oriented with this plane parallel to a housing plane defined by the housing and the main hand grip.
The invention is depicted in an exemplary embodiment in the drawings.